A surfboard is to be understood to mean all customary, essentially flat floating bodies which are suitable for surfing. Sailboards are understood to be the essentially flat floating bodies which are or can be fitted with a sail and are used for windsurfing and the like. For reasons of simplicity, the invention is described below by way of the example of a surfboard for surfing. However, it is pointed out that this does not mean any restriction for the applicability of the invention.
To stabilize the direction, surfboards and sailboards require a so-called fin, a plate which is often of essentially triangular design and whose plane is arranged essentially parallel to the plane of the direction of travel. In addition to the triangular basic shape of the fin, there are numerous modifications, e.g. a design in the manner of the centreboard of a sailing boat, a design in which lines are greatly curved counter to the direction of travel, etc. In addition to the triangular basic shape, rectangular or trapezoidal shapes with straight or curved side edges are also possible.
Surfboards and sailboards are generally made of a plastic material, for example epoxy resin, ABS or similar materials which form the actual rump or body and surround a core made of foamed material, such as polystyrene or polyurethane. Since, for various reasons, the boards have to be designed to be as light as possible, the actual plastic skin can also be of not very thick construction. This therefore causes the problems of mounting the fins on the board with sufficient strength.
In a known type of attachment for fins, an approximately cylindrical depression is arranged on the underside of the board, into which depression the fin is inserted with an elastic bracket of correspondingly cylindrical design. The bracket is expanded by a screw and is thus clamped firmly in the cylindrical depression. However, this type of attachment has the disadvantage that it does not ensure a sufficiently secure attachment, and that it furthermore does not allow the position of the fin to be corrected in relation to the board. An adaptation of the fin position with regard to different external conditions is thus not possible.
An adjustable fin for a surfboard was disclosed by U.S. Pat. No. 4,846,745. This fin is held in a groove which is arranged on the underside of the surfboard and has clamping devices for the attachment of the fin.
U.S. Pat. No. 4,421,492 likewise shows a fin which is adjustable in the longitudinal direction of the board, and in which a longitudinal groove is likewise recessed into the board. The fin can be displaced back and forth in holding grooves by means of pins and is held in the desired position by a spring-mounted part which engages in catch depressions on the underside of the groove. U.S. Pat. No. 4,044,416 also shows a similar construction to the two patents described above.
The abovementioned designs have the disadvantage that, on the one hand, they are relatively complicated and that, on the other hand, the strength leaves much to be desired.
The object of the present invention is therefore to provide a surfboard or sailboard with a fin which can be mounted in a simple and reliable manner, and in which, at the same time, the connection between the fin and the surfboard has a high strength. According to a subsidiary aspect of the invention, it should also be possible to change the position of the fin in a simple manner.
It is furthermore the object of the invention to provide a method for the manufacture of such a surfboard or sailboard.
According to the invention, the object is achieved by the subject-matter defined in the claims. The method according to the invention is also defined in the claims.